Clock striking mechanism



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2 Sheets-Sheet 2 INVENTOR R MAGRO CLOCK STRIKING MECHANISM Flled Jan 17, 1955 July 23, i940.

Patented July 23, 1940 UNITEDl STATES PATENT oFFIcE 2,209,297 CLOCK STRIKING MEGHANIS'M dale, N. Y.

Application January 17, 1935, Serial No. 2,1%

4 Claims.

My present invention relates to a time keeping mechanism and more particularly to an improved striking mechanism for a motor driven timing train.

5 In my co-pending application, Serial Number 695,699 filed October 28, 1933, now Patent No. 2,058,609 granted Oct. 27, 1936. I have described and claimed an improved striking mechanism for motor driven timing trains, such mechanism in- 3 cluding an operating circuit and switches contained therein and forming an essential part thereof.

My present invention is to be considered as an improvement over the invention described and u claimed in my copending application above identifed, and comprises an improved striking mechanism for a motor driven timing train, wherein the striking mechanism and the operating mechanism therefor are entirely mechanical and the n use of an electrically operated mechanism with the pertinent switches therefor is entirely eliminated.

In carrying out my present invention I associate the striking mechanism with the timing u train so` as to have the striking mechanism operated by power derived from the timing train motor and in accordance with a, mechanism directly controlled by the timing train and wherein the usual snail-cam is employed.

m I An important feature of my invention therefore, is an improved striking mechanism for a time keeping clock.

`inother feature of my invention resides in the construction of a striking mechanism for a motor driven clock wherein the striking mechanism and the operating mechanism therefor is entirely mechanlcal.

In carrying out the latter feature of my invention, I provide on the timing train a device operated in synchronism therewith, and which "o automatically sets at any predetermined period, a snail-cam which determines the setting of an arcuate ratchet, which in turn is propelled by a step-by-step device operated and controlled by 45 the timing train. In connection with the timing train is also a cam member which automatically, and at predetermined intervals of time, sets the arcuate ratchet to initiate the striking of the half hour periods. Associated with the arcuate '50 ratchet and with the driving mechanism therefor, is an intermediate device for intermittently releasing the striking hammer which therefore intermittently sounds the striking mechanism in accordance with the predetermined setting of the 55 arcuate ratchet.

A further feature of my invention is an lmproved means for maintaining the arcuate ratchet in its uppermost position from the end of one complete revolution of the snail-cam to the beginning of the next revolution thereof.

Other features of my invention will be referred to in the description of a preferred embodiment of my device,

In the accompanying drawings:

Fig. 1 is a front elevation of a synchronous motor time keeping and striking mechanism embodying my invention.

Fig. 2 is a rear elevation of a clock case showing my invention housed therein.

Fig. 3 is a side elevation of the structure shown u in Fig. i.

Fig. 4 is an enlarged sectional side elevation. of my improved synchronous motor rotating element.

Referring to the drawings, I0 designates a front plate and II a back plate, arranged parallel to each other, and held in parallel-spaced relation with respect to each other by a plurality of posts I2. The elements Ill, il and I2 constitute a framework, in and on which are mounted the various elements constituting a time keeping and striking mechanism embodying my invention. Secured to one end of the posts I2, are lugs or ears I3, and by means of which the framework may be secured in a case i4. Rotatably mounted in sultable bearings or bushings, to be hereafter described, and in the plates I0 and II is a second shaft I5 which carries an indicating hand I6 at its outer end, or the end that projects outwardly from the front plate I0.

Rotatably mounted on the second shaft I5 u is a hollow minute shaft I1 which carries at its outer end a minute hand I8. Rotatably mounted on the hollow minute shaft I1 is a hollow hour shaft I9, such hour hand I9 carrying at its outer end the hour hand 20. The shafts I5,

I1 and I9 have a. common axis and the outer bearing for the hour shaft I9 is mounted in the front plate i0 of the framework above referred to. The shafts I5, I'I and I9 are equipped with various mechanisms which will be hereinafter a particularly described.

Mounted in suitable bearings in the front and rear plates I0 and II respectively, such bearings being in alignment with each other, is a drive shaft 2 I. The shaft 2| extends outwardly beyond the back plate II and secured to this extension is a gear 22. Secured to the back plate I I, as by staking, or in any other convenient manner, is a hub 23 and securely mounted in the hub 23 and 55 extending outwardly from the plate II, or to the right as shown in Fig. 3, is a shaft 24. Rotatably mounted on the /shaft 24 is a bearingv hub 25 oi.'

which forms part of the rotating element of the synchronous motor. Rotatably mounted on the front and left hand portion of the cup-shaped member 21, as viewed in Fig. 4, and abutting against the annular ange 28 is a circular disc 30. The function and operation of this circular disc will be hereafter more fully described.

Frictionally engaging with the outer open end of the cup-shaped member 21 is a second cupshaped member 3|, the outer open end of which is spaced apart from the disc 30. Between the cup-shaped member 3| and the disc.30 is arranged a spring washer 32 having a plurality of arms 33 extending radially outward therefrom, and the outer ends of these arms engage with onesurface of the disc 30, and automatically hold such disc against the annular flange 28. Formed integral with, and extending outward from, the main portion of the cup-shaped member 3| is `a shaft 34 provided on its outer end with a knob or other member 35, and by means of which the shaft 34 and therefore the cup-shaped members 3| and 21 and parts attached thereto may be rotated. The reduced end 26 of the hub 25' is provided with a plurality of passages 36 communicating with the bearing extending through the hub 25 an'd in which bearing is located the shaft 24. The cup-shaped member 21 and 3| constitute a practically sealed chamber which may be filled with any suitable lubricant, and which will furnish lubricantto the shaft 24 in its bearing for practically the life of the device.

The rotating 'element shown in Fig. 4 an'd above described is associated with spaced laminated pole pieces, such laminated pole pieces being mounted on the rear of the plate II by spacing blocks 38. At the end of the laminated pole pieces, remote from the rotating element above described, is a laminated cross bar 39, on which is mounted the energizing coil 40, which takes power from any convenient alternating current source. On the hub 25 are formed teeth constituting a pinion which engages with and drives the gear 22, above referred to as being attached to the extension of the shaft 2|.

Rotatably mounted in aligned bearings in the plates III and II, and arranged parallel to the shaft 2| is a shaft 42. Secured to the shaft 42 is a link 43 provided at one end with a groove or slot 44 which is engaged by a cam 45, secured to the shaft 2|. Also secured to the shaft 42 at a point adjacent to the plate II is a link 46. Referring to Fig. 1 it will he noted that at thel lowermost end of the link 46 is pivotally mounted the lower end of a driving pawl 41, and associated with the pawl 41 is a helical spring 48 which tends to rotate the p awl in a clockwise direction. Again referring to Fig. 1 it will be noted that at the upper end of the link 46 is pivotally mounted a driving pawl 49, and associated with such pawl is a helical spring 50 which also tends to rotate the pawl 48 in clockwise direction. Secured to the "second shaft I5 is a ratchet 5I. with which both of the driving pawls 41 and 49 engage. It will be obvious that as the shaft 2| is constantly rotated under the inuence of the rotating element in the synchronous motor above described, the "second shaft I5 will be intermittently rotated in a clockwise direction by the driving pawls 41 and 49, and the use of such pawls on the ratchet will similate the ticking of the usual spring driven clock. It will be noted that with respect to the ratchet 5I, no holding pawl per se is necessary, as the driving pawls 41 and 48 alternately act in such capacity.

Secured to the second shaft I5, and lying adjacent to the ratchet wheel 5I, is a cam 52 which engages with a slot 53 formed in one end of an arm 54. Such arm is pivotally mounted at one end remote from the slot- 53 on one of the posts I2. An oscillatory movement of the arm 54 about the post I2 as a pivot is therefore imparted by the rotative movement of the cam 52, which as above noted is carried by the "second" shaft I5. Intermediate the ends of the arm 54 is pivotally mounted a driving pawl 55, and associated with the driving pawl 55 is a helical spring 56, which tends to rotate such pawl in a clockwise direction. The driving pawl 55 engages with aratchet 51 attached to the ,minute shaft I1 and the minute shaft I1 is therefore rotated with a step-by-step movement in a clockwise direction. Secured to and extending between the plates I5 and II is a shaft 58, and rotatably mounted on such shaft is a holding pawl 59 which engages with the minute ratchet 51. A helical spring 60, associated with the holding pawl 59, holds such pawl in operative engagement with the ratchet wheel 51.

Secured to the "minute shaft I1 is a pinion 6|, which meshes with and drives a gear 62 rotatably mounted on a stub shaft 63 secured to the inner face of the front plate I8. Secured to the gear 62 and also concentric with the shaft 63 is a pinion'64 which meshes with and drives a gear 65 that is secured to the hour shaft I9.

The relation vbetween the second ratchet 5|, the minute ratchet 51, the gear 65, and the speed of rotation of the shaft 2| is such that the "minute shaft I1 makes one complete revolution every hour, the hour" shaft I8 one com-f plete revolution every I2 hours, and the secon shaft I5 one complete revolution every minute.

The above describes the timing train operated by a synchronous motor. timing train is a striking mechanism.l Such striking mechanism is controlled by devices secured to or associated with the timing train and which devices operate in synchronism with the timing train, in order that the striking may take place at the proper times and bear a proper relation to the time indicated by the timing train.

The means directly associated with the timing train for controlling the operation of the striking mechanism is the well known snail-cam 66, which cam is provided with a series of steps 61, 68' etc. and such cam is mounted on the hour shaft I9. As an auxiliary device associated' with the timing train I have mounted on the minute" shaft I1 a cam 69, which cam is provided with radially disposed indentations 10, and the purpose of these indentations, or the surfaces defining the same, will be apparent as the description of the invention progresses.4

Rotatably mounted in aligned bearings in the Associated with such v front and rear plates I 0 and I I respectively, is a 75 shaft |10. One end oi this shaft H10 extends outwardly upon the front plate l0, and secured to this extending end is an arm 1l. 'Ihis arm ll, at its outer end, has formed integral therewith an arcuate ratchet member 12. On the arm 1i, intermediate the ends thereof, is a laterally ex tending pin 13 which is adapted to engage with the various steps 61, 68 etc. formed on the periphery of the snail-cam 66. The pin i3 on the arm 1I, in its engagement with the various steps ti, 68 etc. of the snail-cam 66, determines the extent of downward movement of the arcuate ratchet member 12, and thus, as will he hereinafter ex plained, determines the number of blows permitted by the striking mechanism. The pin 'i3 on the arm 1l, in its engagement with the steps of the snail-cam t6, determines the striking of the hours indicated by the timing strain hereto fore described, and in addition to these means I have provided auxiliary means for determining the setting of the arcuate ratchet i2 for the purpose of determining the striking of the half hour periods.

This latter device consists of the following. Secured to the shaft Htl, intermediate the ends thereof, is an arm 14 which lies substantially parallel to but spaced apart from the arm 1i. @n the cam 68 are laterally extending pins 'it and l15 respectively, which in the rotative movement of the cam Se engage with the arm 'it and thus determine not only the setting oi the arcuate cam 12 for the purpose of initiating the striking of the half hour periods, hut also maintain the pin 13 in its uppermost position after the striking of the half hour following noon until the cam 61 designating one oclock, has moved into a position beneath such pin i3.

The normal position of the arcuate ratchet 'l2 is determined by the engagement of the pin it with one or the other of the cams S1, t8 etc.

At the end of the link I3 remote from the slot 44 is pivotally mounted the lower end of a driving pawl 16, which pawl engages with the teeth in the arcuate ratchet 12, and on the oscillation o the link 43 steps the arcuate ratchet 12 upward from the position shown in Fig. i to its uppermost position.

Mounted in aligned bearings in the front and rear plates il) and il respectively is a shaft 11, and secured to this shaft is a sleeve 18, to which is attached one end of a pawl 19, and which pawl engages with the teeth in the arcuate ratchet 12 and acts as a holding pawl therefor. A helical spring on the shaft 11, and cooperating with the holding pawl i9, tends to rotate such holding pawl in a counter-clockwise direction, and into position to be in engagement with the teeth of the arcuate ratchet 12. Immediately preceding the Ystriking operation, both the driving pawl 16 and the holding pawl 19 are released from the teeth of the arcuate ratchet 12, which thereupon falls from its uppermost position into a position determined by the engagement of the pin 13 with one or the other of the steps 61, 68 etc. of the snailcam 66 and/or by the engagement of the arm 14 with the pins 15 and |15 respectively carried by the cam 68.

The striking operation therefore takes place on the upward step-by-step movement of the arcuate ratchet 12 because of the intermittent engagement thereol by the driving pawl 18.

The release of the driving pawl 16, and the holding pawl 19, from the arcuate ratchet 12, is performed by the following instrumentalities and in the following manner. Rotatably mounted in aligned bearings in the front and rear plates it and il respectively, is a shaft 8l. Secured to such shaft Bl is an arm 82 which extends generally downward, as viewed in Figs. l and 3, and has its lower end cooperating with the cam plate t9. Secured to the shaft 8l is a hub` 83 and secured to such hub 83 and extending downwardly therefrom is a resilient member' tit. This resilient member t4 extends downwardlly, and as the shaft 8i is rotated, for example in a counter-clockwise direction, as viewed in Fig. l, the holding pawl i9 and the driving pawl it for the arcuate ratchet l2 lie in the path of movement of the lower end of the resilient member 84. Therefore upon rotation of the shaft 3i in the direction noted, it la apparent that the resilient member 8i will engage th the driving pawl it and holding pawl iii, and will move them out of engagement with the teeth of the arcuate ratchet 1i?, thus allowing such arcuate ratchet to drop from its uppermost position into a position as determined either by the cooperation of the pin i3 with one or the other of the steps iii, t@ etc. oi the snail-cam @t and/or the engagement of the pins iii and iit respectively with the arm ill. The lower end oi the arm B2 is always in engagement with the cam plate t9, and thus follows the contour of such cam plate, including those surfaces which denne the openings 'it in such cam plate.

Assume that the apparatus is in the position indicated in Fig. l, and therefore, that the lower end of the arm t2 is in engagement with the edge oi the cam plate S9, and for the moment is located at the bottom of one oi the cutouts it. As the cam plate 88 rotates in the direction of the arrow shown in Fig. l, that is in a clockwise direction, it is obvious that the end of the arm t2 will ride up on the curved edge or the cam plate te dehning one sideoi the cutout 'Jil and therefore, the lower end of the arm t2 will move to the right as shown in such Fig. l, thereby rotating the shaft 8i in a counter-clockwise direction, and simultaneously moving the lower end of the resilient member 8d to the right and into engagegent with the driving pawl "i6 and holding pawl Rotatably mounted in aligned bearings in the iront and rear plates l0 and il respectively is a shaft S5. Secured to such shaft and extending radially outward therefrom is an arm 86. The outer end of this arm 86 is normally in engagement with the upper end of an arm 81 secured to, and extending upwardly from, the shaft 11. Secured to the shaft is a hub 88 and attached to such hub 88 is a resilient striking rod 89, provided with a striking hammer or similar instrument at its lower end. Secured to the shaft 42, and extending upwardly therefrom, is an arm 9|, the upper end of this arm being adapted to be brought intermittently into engagement with the resilient member 89 for a. purpose to be hereinafter described. Secured to the shaft 8l is an arm 92, which upon rotation of the shaft 8l in a counter-clockwise direction engages with the arm B8 and lifts the same out of engagement with the end of the arm 81.

The relation of the arm 86 with respect to the arm 81 is such that the holding pawl 19 may re" main in engagement with a tooth of the arcuate ratchet 12 upon rotation of the shaft 11, after the upper end of the arm 81 has moved out of engagement with and from beneath the end of the arm 86. Associated with the striking rod 89, and striking hammer 90, for the purpose of sounding the time is any convenient sound emitting device,

such for example as the metallic rod 93 Asecurely anchored in a block 94 or other suitable base.

The striking operation takes place as follows: Referring to Fig. 1, it will be noted that the pin 13 is in engagement with the lowest step of the snail cam 66, or in other words the arcuate cam 12 has been permitted to fall into a position to cause 12 oclock to be struck by the striking mechanism. It is understood of course, that the mechanism shown in Fig. 1, and particularly the cam disc 69 and snail cam 68, are rotating in a clockwise direction, or in the direction of the arrow shown in Fig. 1. As shown in Fig. 1 the radially extending edge or face 96 of the cam disc 69 has just passed beyond the lower end of the arm 82 which is attached to the shaft 8|, and the arm 82 therefore has fallen into the depression 10 in such cam disc 69, thus rotating the shaft 8| in a clockwise direction, and bringing the arm 92 downwardly out of engagement with the end of the arm 86; bringing the resilient member 84 to the left away from the driving pawl 16 and the holding pawl 19; allowing such driving and holding pawls respectively to be brought into operative position with respect to the arcuate ratchet 12. 'I'he upper end of the arm 81 therefore assumes its proper position under the end of the arm 86, thus holding for the moment the striking member 89 and hammer 98 in inoperative position, and in the position shown in such Fig. 1.

It being understood that the driving shaft 2| is constantly rotating, it is obvious that the link 43 is constantly oscillating, together with the shaft 42 and all parts attached thereto, and that because of the position of the cam 45 in the slot 44 the next movement of the link 43 will result in a downward motion of the end of such link, to which the lower end of the driving pawl 16 is pivotally attached. Therefore the driving pawl 16 will move downward and its upper end will engage in the next lowermost tooth of the arcuate ratchet 12. Simultaneously with such movement the arm 9| is oscillated, because of the oscillation of the shaft 42, and the upper end thereof will engage with the member 89, thus rotating the shaft 85 in a counter-clockwise direction, and moving the outer end of the arm 86 upwardly so as to permit the upper end of the arm 81 to be positioned thereunder, if such movement has not already taken place.

'I'he link 43 continuing its oscillatory movement, the next step will be an upward movement of the driving pawl 16 which will move the arcuate ratchet 12 upwardly about the shaft |10 through the space of one tooth and in such movement the upper end of the holding pawl will ride up on the tooth with which it happens to be at this time in engagement, thus rotating the shaft 11 in a clockwise direction, and moving the upper end of the arm 81 out from under the end of the arm 86. Immediately such arm is freed, the weight-of the arm 86, together with the weight of the hammer 90, and the member to which it is attached, will rotate the shaft 85 in a clockwise direction and the hammer 99 will engage with the sound emitting element 94, thus striking one blow.

By this operation the end of the holding' pawl 19 has come into position under the face of the rst uppermost tooth of the arcuate ratchet 12, and the arcuate ratchet 12 will thus be held in the position to which it has been moved by the driving-pawl 16. The driving pawl is now moved downward and the arm 9| rotated to the right thus moving the arm 89 tothe right. and rotating the shaft 86 so as to move the end of the arm 88 into the position now shown in Fig. 1. During this movement the end of the arm 92 necessarily contacts with the side or inner face of the arm 81, as viewed in Fig. 1, thus slightly rotating the shaft 11 .in a clockwise direction, and causing a slight outward movement of the upper end of the holding pawl 19 with respect to the tooth of the arcuate ratchet 12 with which it is inengagement.

This outward movement of the upper end of the arm 81 however, is insufficient to remove the upper end of the holding pawl 19 from engagement with the tooth of the arcuate ratchet 12. and therefore the parts are again in the position shown in Fig 1. This sequence of operations is repeated, the arcuate ratchet 12 moving upward step-by-step through the space 'of one tooth at each step, and at each step the hammer 90 engages with the sound emitting device 94, until the arcuate ratchet 12 reaches its uppermost position, when the striking stops. The driving pawl 16 is subjected to an intermittent motion during the operation of the timing train, but after the be imparted to it, as the driving pawl 16 rides on the plain surface 91 of the arcuate ratchet 12.

During this striking operation the cam plate 69 and the snail-cam 66 rotated in a clockwise direction, pin 13 on the arm 1| gradually approaching the practically radial face 94 of the snail-cam 66. With each step upward of the arcuate ratchet 12, a similar step is also imparted to the pin 13, and therefore by the time the last blow is struck by the hammer 98, such pin 13 will be moved radially outward with respect to the axis of rotation of the snail-cam 84 a distance greater than the radial distance of the cam surface 61. During the continued rotation of the cam plate 69, the lower end of the arm 82 also engages the cam surface 98 of the cam disc 69, thus rotating the shaft 8| in a counterclockwise direction, and moving the end of the arm 92 upwardly into engagement with the end of the arm 86, and such arm 92 holds the arm 86 upwardly, thus putting the striking hammer 90 out of operative condition, regardless of the movement of the arm 81.

position. Also the resilient member 84 will move into engagement with the driving pawl 16 and holding pawl 19, and the arcuate ratchet 12 will again drop into the position shown'in Fig. 1.

The hour having been struck, and the minute ratchet 51 rotating in a clockwise direction at the rate of one resolution per hour, before the 30 minute period has elapsed, the pin 15, carried thereby will engage with the arm 14, rotating the shaft |16 in a counter-clockwise direction and raising the arm 14, and arcuate ratchet 12, until the pin 13 on the arm 1| occupies a position one step beneath that to which it was moved on the striking of the previous hour, or in other Words, in position for the driving pawl 16 to effectively operate on a single, and the lowermost tooth of the arcuate ratchet 12.

Shortly after the striking of the half hour the end of the arm 82 will ride up on the curved face 98 of the notch 10, thus moving the arm 92 into position to prevent further operation of thestriking hammer 90, and also moves the resiiient member td into position to release both the driving pawl 16 and the holding pawl 'i9 from the arcuate ratchet l2. Under ordinary circumstances, and as is the case with every other hour period except the l2 oclock period just described, the dropping of the arcuate ratchet 'i2 to its lowermost position brings the pin 13 on the arm 'Il into engagement with the cam face, as for example the cam face El, 58 etc. The pin l on the arm 'li after the half hour has been struckon every hour except the 12 oclock hour just referred to will ride on the surface of the step of the snail-cam until the next succeeding hour, when it will drop off onto the next lower cam. At the 12 oclock period, which has just been described, such a method of operation is impossible, as the 12 oclock cam is the lowermost cam oi the series on the snail-cam 66, and it is necessary therefore, after the striking of the half hour period between 12 and l oclock, to maintain the pin 13 in its uppermost position so as to ride on top of the cam face 6'! when the snail-cam 66 rotates a sufficiently great distance. This is accomplished by providing the pin H5 on the minute ratchet 51, and which pin |15 comes into operation after the pin 15. The pin H5 will engage with the arm 14 after such arm has been acted upon by the pin 15, and the arm-'I4 will be maintained in its uppermost position, and therefore the pin 'I3 on the arm 1I will be held in a position to ride up to vthe cam face 61 on the rotation of the snail-cam.

While I have necessarily shown and described the preferred embodiment of my invention somewhat in detail it is to be understood that I may vary the size, shape and arrangement of parts comprising the devices within relatively wide limit without departing from the explanation of the invention.

I claim:

1. An improved striking mechanism for a synchronous motor driven time keeping mechanism, comprising a sound emitting device, a pivoted hammer adapted to engage therewith,` means for normally holding said hammer in inoperative position, an arcuate ratchet, a snail cam associated with the time keeping mechanism for controlling the setting of the ratchet to determine the number of blows tofbe struck by the hammer, a driving pawl for intermittently and positively moving the ratchet step-by-step, a holding pawl for maintaining the ratchet in the position to which it has been driven by the driving pawl and for periodically releasing the hammer in accordance with'the movement of the ratchet.

2. An improved striking mechanism for synchronous motor driven time pieces, comprising a sound emitting device, a pivoted hammer adapted to engage therewith to cause a sound emission from said sound emitting device, a lever associated with said pivoted hammer for rotating said pivoted hammer into engagement with the sound emitting device by gravity, an arcuate ratchet, a snail cam operated by the time piece for determining the setting of the arcuate'ratchet to determine the number of blows to be struck at any particular setting by the pivoted hammer, a pivoted link associated with and oscillated by the time piece, a driving pawl carried by the pivoted link and engaging the arcuate ratchet to propel the arcuate ratchet intermittently step-by-step from its set position, a holding pawl for maintaining the arcuate ratchet in position to which it has been moved by the driving pawl, a holding means for the pivoted hammer, and means associated with the holding pawl for intermittently releasing the holding means for the pivoted hammer in accordance with the movement or the ratchet.

3. An improved striking mechanism for a synchronous motor driven time keeping mechanism, comprising a sound emitting device, a pivoted hammer adapted to engage therewith to cause a sound emission therefrom, means for normally holding said pivoted hammer in inoperative position, a snail cam driven by the time keeping mechanism for controlling the setting of the arcuate ratchet to determine the number of blows to be struck by the pivoted hammer, a pivoted link connected to the time piece and oscillated thereby, a driving pawl associated with the pivoted link and positively driving the arcuate ratchet step-by-step, a holding pawl for maintaining the arcuate ratchet in the position to which it has been driven by the driving pawl and for periodically releasing the pivoted hammer in accordance with the movement of the arcuate ratchet, and means driven by the time keeping mechanism for returning the pivoted hammer to normal inoperative position.

4. An improved striking mechanism for a synchronous motor driven time keeping mechanism comprising a Asound emitting device, a pivoted hammer adapted to engage therewith, an arcuate ratchet, a snail cam associated with the time keeping mechanism for controlling the setting of the ratchet to determine the number of blows to be struck by the hammer, means for intermittently and positively moving the ratchet step-bystep, a holding pawl for maintaining the ratchet in the position it has been driven by the last named means and for periodically operating the hammer in accordance with the movement of the ratchet.

RALPH MAGRO. 

